Telephone system



Aug.-26, 1941. F. BEERMAN ETAL 2,253,998

TELEPHONE SYSTEM Filed Apr11 20,1939 11 sheets-sheet 1 Aug. 26, 1941.

' F. BEERMAN ETAL TELEPHONE SYSTEM A Filed April 20, 1939 11 'Sheets-Shea?l 2 Aug. 26, 1941. F. BEERMAN ET AL TELEPHONE SYSTEM Filed April 20, 1939 l1 Sheets-Sheet 5 Aug. 26, 1941. F. BEERMAN ETAL TELEPHONE ySYSTEM Filed April 2o, 1959 ivsmolw Emulex-:Bmw

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MAPnN HEBEL.

Aug. 26, 1941. F1 BERMAN ETAL '"2,253,99s

TELEPHONE SYSTEM Filed April 2o, 1959 1l Sheets-Sheet' Nm Hamm.

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TELEPHONE SYSTEM Filed April 20, 1959 1l Sheets-Sheet 8 ad) ATT( NEYS.

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Aug. 26, 1941.

. BEERMAN ETAL TELEPHONE SYSTEM ll Sheets-Sheet 9 Filed April 20, 1959 MA mw HEBEL.

Aug. 26, 1941. F. BEERMAN E'r AL TELEPHONE SYSTEM Filed April 20, 1939 ll Sheets-Shea?l l0 Eempmcu BEERMANN k MAnrwJ-km ATTaRNEa/S.

Aug. 26, 1941. v F. BEERMAN ErAL TELEPHONE SYSTEM Filed April 20, 1959 11 Sheets-Sheet l1 Amm/sm Patented Aug. 26, 1941 Friedrich Beermann, Munich, and Martin Hebel, Oberbayern, Gernariy Application April'co, 1939, seriariyo. 268,930

In'Germany April 23, 1938 Claims.

' This invention relates to automatic Vtelephone systems.

Insuch systems `connections arefgenerally made directly by the calling subscriber who causes im-V essential particulars of all calls from which the` charges to be made can be evaluated or with devices which evaluate the charges directly. The above-mentioned devices are actuated by impulses which are sentout when the calling subscriber dials and which are used to build up the wanted connection.

Where the system comprises a large number vof exchanges, it is desirable that a calling subscriber should be able to make his call through anoperator if he should so desire. In such cases, he can connect himself to the operator bydialling a particular digit or series'of digits such as 00. As the impulses used in'making the connection to the wanted subscriber are sent out not by the calling subscriber but by the operator, they cannot be used for actuating the devices mentioned above, for selecting the shortest route, evaluating the charge and so on if', asis usual, 'these devices are situated between theoperator and the calling subscriber. The operator therefore has to do what is necessary herself.

YThe invention is concerned with the problem of reducing the amount of work to be done by the operator in these circumstances. Y Y

The systems with which the invention is concerned comprise a number of exchanges 'which are arranged so as to enable a subscriber to make a connection fully automatically or semi-automatically through an operator. `When a connection is made through the operator, impulses sent out by the ylatter tok extend 'the connection towards the wanted subscriber are also transmitted backwardly over the connection already made between the calling subscriber and :the operator and, while being so transmitted, cause apparatus to be actuated as it would have been actuated by the impulses transmitted forwardly had the connection been fully automatically made bythe subscriber himself 'without ythe `help ofthe operator.

This considerably simplilies the 'operators work and therefore, allows 'her to "deal with a greater number of callsin a given time.

n kThe invention can be applied to `systems in which a connection is made with the help of more "than one operator,4 `for example where an operator whohas received the calling subscribers instructions passes these onto-an operator at a more distantfexchange who then dials the Wanted' number. In'that"casefthe impulses which are sentout by theiilst cpeiator in 'order-to extend the nc'on'nectit'jn to "the 'second 'p'erat'r are also transmittedeba'ckwardly towards the calling sub-4 scriber. These can'be 'used Ato identify 'the xcnange at' which the second operator is situated; The "r'st "operator can then 'transmit "to 4the sec# ond-operator-impulseswnich 'are also transmitted backwardly 'towards the callingsubs'crber sdthat the various-particulars 'of the' connecticnr'ecorded'some at "thesecondppeatdns exchange and somebetween 'the first 'operators exchange and the calling' subscriber can 'bebo-related. This considerably sirnpliiesl the char-ging f long distance'calls. v Y

An example o'f 'the construction and operation of a system in accordance with the invention will now 'be ldescribe-d with Yref@rence to 'the accompanying=drawings iniwhich;

:Figure 1 'showstheessential circuits of a nd'r' in "a lterminal -exchange `in a system illustrated diagraminatically in 'Figure'9. l

Figure'2 showsthe essential circuits of "a repeater in a "terminal "exchange at the ,outgoing end'of aline.

Figure 3 'shows'the essential circuits 4o'f a'rpeater in a subsidiary group exchange Zat 'the incoming'endo'f the line. Y

Figure '4 shows `the essential circuits ofthe selectors in thesubsidiary group exchange.

'Figure `5 vshows Vthe essential circuits of Ythe repeater in the subsidiary'group vexchange atthe outgoing end of 'a line.

Figure '6 shows the essential circuits of a rep'eaterofamain group exchange at'the incoming end of aline.

erators vpositix'anat the main group exchange and `Fig'ur'e'8 'shows the essential circuitso'f anal selector. Y Y igure 10'illustratesdiagrammaticauy'how the' systeminustrateu in Figure `9 can be adapted to maken. suitable ror long distance'calls.

Figure 11v shows the 'essential vcircuits o'f anperators pcsition'in a central-exchange of the sys-y tem illustrated in Figure'lO, and

Figure 12 shows'the'ess'ential circuits of a long distance operators position at 'the/*central 6X- change. n v l The System angst-rancia -91 @crap-rises 'a main group exchange HA,"towhichfai'e connect-,-

ed a number of subsidiary group exchanges such as that shown at KA. Each subsidiary group exchange has connected to it a number of terminal exchanges such as that shown at EA. When a subscriber of the terminal exchange EA removes his receiver he is automatically connected by a iinder AS to an impulse responding switch MLWI. If the subscriber wishes to make a connection outside his own exchange he has to dial 0. The impulses thus sent out act on the switch MLW which on receipt of the fifth impulse causes a hunting switch SWI to seize a free line VLI. The 7th, 8th, 9th and 10th impulses are then transmitted over a wiper of the switch MLWI to the repeater l and thence to the line VLl. These impulses are received in the subsidiary group exchange KA by the repeater 2 and are transmitted to an impulse responding switch MLWZ, which, on receipt of the iirst impulse (the 7th of the train) causes a hunting switch" SW2 to seize'a vfree `line VLZ. The fourth impulse (the 10th of the train) is transmitted over a wiper of the switch'MLWZ to the repeater S and thence to the line VLZ; The repeater in the main group exchange HA is thus seized.

The calling subscriber then dials the number of the Wanted exchange. Further impulse trains are thus transmitted over thelines VLI and VLZ. Of these trains, the first acts on the switches MLWI and 2 and sets the group selector GWI in the exchange HA; the second and subsequent trains set other group selectors (not shown) If the subscriber has dialled the number of the exchange KA through which runs the connection which has been made to the main group exchange HA, the switch MLW seizes a hunting switch SW which seizes a free group selector GW4 in the exchange KA. The line VL2 and the connecting apparatus at the exchange HA are then released. l

YThe repeater 2 at the exchangeKA has associated with it a device ZD for recording details of the calls from which the charge to be made can be evaluated. All impulses sent out by the calling subscriber act on this device ZD.

IThe main exchange HA includes an operators position VP. If the subscriber wishes to make a connection through the operator he irst dials 0 as explained above and then dials 0 again. The group selector GW! is thus set on a line PL (Figure 7)' leading to the operators position VP and to which a second group selector GW2,is connected. The operator is then connected to the calling line by a switch SW3 and can take the calling subscribers instructions.

' The impulses sent out by the operator are transmitted over a wire of the speech line to the group selector GW2 which extends the connection to a group selector GW3 in the desired direction. The impulses are transmitted backwards at the same time over another wire of the speech as far as the'fnder AS in theV calling subscribers exchange EA. VThese impulses act on a switch MLWS in the repeater U4, on the switch IWLWZ in the subsidiary group exchange KA and on the recorder ZD. If the connection is to be extended backwards from the exchange HA, the impulses sent out when the operator'dials the number of the wanted exchange c au'se the switch MLWS to disconnect the group' selectors GWZand GWS. Alsotheswitch,l\/LLW2 causes the hunting switch SW4`to seizev a free group selector GW4. The further impulses sent out by the operator are received' by this group selector GWA which makes the connection to the wanted subscriber by means of further selectors which are not illustrated, The impulses which are transmitted backwards to the nder AS are used to actuate the apparatus serving for the evaluation of the charge and also the switches which serve to ensure that the connection is made over the shortest route.

The circuits are the same whether the operation is semi-automatic working, i. e. the calls are made through an operator, or fully automatic. The construction and operation of a system in accordance with the invention will now be described in detail. If the operation is fully automatic, the calling subscriber sends out all impulse trains for effecting the connection and after the last impulse train has been sent out from the nal selector, a backward signal is sent which indicates whether the wanted subscriber is free or engaged and causes an appropriate signal to be sent to the calling subscriber from the finder in his exchange. When the wanted subscriber removes his receiver, a second backward signal is sent out by the nal selector by means of which the speech circuits are closed in the repeaters. Also, the device which records particulars of the call is acted upon for the duration of the connection. When the Wanted subscriber replaces his receiver, a third backward signal is sent from the final selector. This signal opens the speech circuits. A transmitting device in the finder transmits impulses corresponding to the number of the calling subscriber to the recorder and the connection is then released.

If the operation is semi-automatic, the calling subscriber first connects himself to a free operators position whereupon a backward signal is transmitted to him. A second backward signal is transmitted to the calling subscriber when the operator removes his receiver. This signal closes the speech circuits in the repeaters. Before the operator dials the wanted number, she causes a third backward signal to be transmitted. This signal is different from that which, in fully automatic operation, indicates that the called subscriber has replaced his receiver. It only causes the speech circuit to be opened and prepares the connection between the operator and the calling subscriber for the transmission over it of the impulses now to be dialed. When the connection to the wanted subscriber is nally made, the three backward signals are repeated in succession by the nal selector. The signal which indicates re'- placement of the called subscribers receiver, as in the case of fully automatic operation, causes the number of the calling subscriber to be determined and the connection to be released.

It is not necessary that the number of the calling subscriber should be determined at the end of the conversation. It can be determined at any stage, for example, after transmission of the backward signal indicating that the called subscriber is free.

For the evaluation of the charge to be made, a device can be used which records all essential particulars of the connection, or else a time-zone metering device can be used which transmits a number ofA impulses to the calling subscribers meter in accordance with the number of the wanted exchange and the duration of the conversation. In the latter case, it is not necessary to ascertain the number of the calling subscriber.

Where the operation is fully automatic. the. procedure is as follows:

-When a subscriber of the terminal exchange EA removes his receiver, the relays INI, IAI, and

message 'main .group exchange .HA.and, if. required, those inthe.isubsidiarygroupexchangeKA to be set.

IBI .of .a .freender AS (Figure .1) are Aenergised @verra wireAnl. This (inknownimanner)-.causes thezwipers .of the;nder to .be set yon .thercalling ,subscribers .line so .that the .re1ay..IC' 'responds and its Icontacts .Ic3and .ICA .connect the windings IA2 and IB2 .to the speech line. The relay .IE iis energised over the contacts Ic5, m2 and Ia.I. .The contacts IbI andIeI connectthe source .of .alternating current :AZ .which transmits dialling .tone ,to the callingsubscriber. .Acircuit is closedfthroughfthe.line vlcI byr means of the conltact vhr3 .so .that the impulse responding `switch MLWI .(Figure 9) which is not illustrated .in detail .is seized.

=If .the subscriber wishes to makea connection to Ja subscriber .of vanother exchange, `he v'lrst dials (l.V .This .causes the relay .IA to vbe .intermittently de-energised. The contact `Intl ltransi mits theecurrent impulses to theline lal. At the rst impulse, therelay IB drops-and .the contact -I.b2 short .circuits :the .winding IB2. so that the Y relayzIB cannotrespond. The contact Ibl disconnects the LA. C. source AZ.

The .impulses Aof the .first .train .actuate lthe switchMLWI (Figure). On receipt of the 5th impulse, thisswitch causes a free-hunting switch SW-I to seize a freerepeater 'I (Figures -2A and 9). In therepeater Lthe relay 2C is energised' in known manner. On receipt of the VI7th impulse, the switch MLWI closes an impulse transmitting circuit through the repeater I. VThe 7th and Subsequent impulses are received by the relay 2A in the repeater I. At each energisation of this relay, the contacts `Zal 42d2 .send an A.r C. impulse through the connecting line VLI.

In the repeater 2 (Figure 3), the A. C. iinpulses are received by a relay 31 which energises the relay 3A., The contact Salv transmits the impulses through the line la3. The iirst impulse energises the relays 3C and 3E which remain energised for the duration of the connection. The contact Sci closes a circuit through the .line BD leading to a `device ZD which records the essential particulars of the connection. The con- Thelast two-impulsetr-ainsact on annal selector LW (Figure .8) inthe vwanted.subscribers ex- (change .which is seized by .the 'previous .group selector through .the line lc8 so that the relay 9C is energised. .'Ihe Wipers of the nal selector :are Seton the-contacts of the Wanted'subscriber in Vknown manner by a rotary and an axial move,- Inent. `,The contacts 9k are .thrown durinfr the axial movement and `the contacts Sw during the rotary-movementf WhenH the last train has been received, asloW- to-release relay 9V whichwas energised by the impulses, dropsso that its contact SUI unlocks the slow-to-release relay 9E Ywhich has so far "been energised. A 'circuit for the testing relay 2@Pis-closed Vfor theduration of the delay in relea'seof ythe .relay ..9E. 'If the YWanted. subscriber is free, the-relay 4QP can respond; liivhe is =.en

gaged, the relay SP remains de-energsed. If the subscriber .has La .number of lines, the final `selectorucan .be automatically. stepped until a -free .line .is found. @For r-this purpose, the relay :BAis energi'sedin acircuit running through the Wiper .Zwr/, the stepping being :effected -byinter- Y action of the relays 9A and 9V.

tact 3ct3 transmits the yimpulses simultaneously Y to the line JD vand Vthus to the recording deviceZD.

' The impulsesA are also transmitted over .the line M3 Yto the relay 4A of the switch MLWZ (Figure 4) The relay IIC is-energised ina circuit running through'the line Zc3. The contact 464 -closes a circuit for the driving magnet 'IIDS for the hunting switch SW2 which seizes 'the repeater S of a free line V112. The relays ylli (Figure 4) and 5C (Figure 5) are then energised over the line lc. The relay 4P vconnects the speech line. The lastrfour impulses ofthe rst train which act on the relay IIA cause the wipers dm of the switch MLW2 to be stepped through four steps. At the fourth step, the Wiper dm@ connects the line Za3 to the line Zad. The 4th impulse thus inuences the relay 5A of .the repeater 3 (Figure 5) which sendsout an A.-C. impulse Vto the line VLZ.v In therepeaterII (Figure 6)., this impulse is received by the .relays6J.,'A. The .relays 5C andSE areenergised and remain energsed throughout the Yduration of the connection. The contact16c3 Acloses vfacirf euit'through the line lc'through whichthe group selector GWI seized. 1 y Thefsubs equent impulse trains .sent outlby the calling subscriber cause 'the sgroupiselectors vinl'th'e which is Vnot .shown Lin detail Visi- If,fthe wanted subscriber being engaged, :the lrelayl? .doesnot respond, `a backward signalling circuitis `closed by .the vcontacts 91122, @5,9115 through the :line ZUB whenthe relay -SE drops. ltwillbeassumedthat the line ZbS'is directly connectedto the line-Z175 (Figure 6) through one or vmore .group selectors. .The relaySK is ene'rgised in the backward .signalling Ycircuit and nits contact 6lc3 energisesv-a rslowacting relay v(5L. The relay BS .is energised for the duration-of the delay vin response of the relay L and -sendsout ashort A. C. (impulse :through the line V112. In the Lrepeater (Figure y5), this impulse is received 'by the krelay `5'l.'which,"by means of its contact''eIgrst'energises the'relayEY and then the relay 5X. The-contacts 504, 5ml', Syl and 5g-2 then close afbackward lsignalling circuit throughfthe line Z214 which-is connected to the line"lb3. Inthe repeater v (Figure '3), the relay3K responds and .by acting on the relays 3L and `3S causes anAQC. impulse'tobe sent over the line VLI. In the repeater I (Figure 2), the relay 2E responds and energises therrelays ZY and 2X. The contacts 2xI, ZyI close a backward signalling circuit through thelower speech'wire which is connected to the iinelbl. (Figure 1). In the finder AS, theV relay yIM is renergised and energises the relay IS. The. contacts Island Im3 short circuit the winding 2 of the relay IN. The connection is released when the relay .IN drops. The A. C'..source BZ .is connected by the contacts Imi and Ieand transmits a busy signal to the calling subscriber. 'If a group selector cannotriind a Vfree line, .an appropriatebackward signal isV sentout which causes the connection to be `released andthe busy lsignal' to be emitted,

' If, y.the Wanted-subscriber being free, the relay Sil?-A (Figure 8) canrzrespond, the contact p is thrown but the relay .9E has not yet dropped. The ,backwardsignalling circuit through the'line Z218 Vis thus closed only for the duration of the dlayinrelease of the relayfSE. On-response of the rrelay "6K (Figure A(i) which" is Vconnected to theV line Zb by the linelban A. -C.` impulse 'i's .sent through ythe lineVLZ by the relay (5S asnin the lease of thej-busy signal;V Whenthe'back- 6K drops.

ward signallingcircuit is opened agaimthe relay For the duration of the delay in release of the relay 6L, the relay 6S is again energised and sends a second A. C. impulse to the line VL2. Also, the relay B'Iis energised and is locked. If the repeater 3 (Figure 5)., the relays vSY and X are again energised by the rst A. C. impulse of the idle backward signal. The second impulse of this signal de-energises first the relay EY and then the relay 5X. rI'he Abackward signalling circuit through the line-Z194 is thus closed only for the duration of time which elapses between the receipt of the two impulses. When the relay EY drops, the relay 5T is energised and locked. In ythe repeaters Z (Figure 3) and I (Figure 2), the same operations are effected as in the repeaters and 3. Also, the relays 3T and 2T are energised and a backward signalling cir-cuit through the line Zbl is momentarily closed.

`In the finder AS (Figure 1), the relay IM momentarily responds and the relay IS energises, When the relay IM drops, Ythe relay lD is energised by the contacts Isl and lmS, is locked by its contact ld2 and opens the circuit for the relay IE. IThe contact ld3 removes the short circuit from the winding 2 of the relay ,IB so that the latter responds again. For the Yduration of the relay in release of the relay IS, the A. C. source VZ is connected upr by the contacts ldl and Is3 and sends a short idle signal to the calling subscriber. The A. C. source FZ is then connected up by the contacts |33 and sends an intermittent idle signal to the calling subscriber.

In the final selector (Figure 8), the relay 9L has in the meantime been energised and connects a source of ringing current to the Wanted subscribers line. When the wanted `subscriber removes his receiver, the relay 9U is energised and opens the circuit for the relay 9L and energises the relay 9Y. The calling sub-scribers feed circuit includes the relay SY'and the winding 3 of the relay 9A. The contact 9115 closes a circuit for the relay 9V which includes a resistance R which causes the response of the relay QV to be delayed. For the duration of the delay in response of the relay 9V, the backward signalling circuit is closed through the line Z198 by the contacts 9y4 and 9124. An A. C. impulse is sent to the line VL2 by the relays 6K, 6L and BS (Figure 6) at the beginning and at the end of this backward signal which indicates .that the subscriber has removed his receiver.

When the relays 6K and 6L are energised, a circuit is closed for the relay 6P which is then locked. When the relays K and BL drop, the relay 6G is energised and its contacts Igl and 692 close the talking circuit. In the repeater U3 (Figure 5), the relays SY `and 5K are energised on receipt Vof the first A. C. impulse of the backward signal indicating that the called subscriber has removed his receiver, and close a backward signalling circuit through the line lb4 and energise the relay 5P. On receipt of the second irnpulse, the relays SY and 5X drop and close a circuit for the relay 5G sothat the contacts 592 and 593 close the talking circuit and open the backward signalling circuit. The same operations take place in the repeaters Z (Figure 3) and l (Figure 2), the relays 3P, 3G and 2P, 2G being energised. v

the repeater 2 (Figure 3), a circuit UD for a device for recording particulars of the co-nvnection is prepared by the contact 3g4 which is periodically closed by a contact u and causes the duration of conversation to be recorded. The relay 4G in the switch MLW2 (Figure 4) which closes the talking circuit is energised by the contact 3g5. In the nder AS (Figure 1) the relay IM isl momentarily energised by the backward signal denoting the removal of the called subscribers receiver. The contact Im3 opens the circuit for the relay ID which drops after a delay. For the duration of this delay, the relay IG is energised by the contacts Im, Idil Iand. is locked by the contact lg4. The contacts Ig2 and Ig3 close the talking circuit. When the calling subscriber makes a fully automatic connection to an exchange other than his own, the impulse which is sent out when the called .subscriber removes his receiver is of such a length that the relay ID drops before the relay IM. In the case of local calls, i. e. to a subscriber belonging to the calling subscribers own exchange, the corresponding impulse sent through the line Zbl is so short that the relay IM drops before the relay ID.

In the case of a local call, when the relay IM has dropped, a circuit for the line ld to which the calling subscribers meter Z is connected is made by the contacts I g4, Idil and lml. The meter is thus moved forward by one step. The case of calls made outside the calling subscribers exchange, the meter is not actuated, the charges being evaluated from recorded particulars of the call. When, at the end of the conversation, the c-alled subscriber replaces his receiver, the relays SY and 9A (Figure 8) drop and the ycontacts Syl and 911| close a backward signalling circuit through the lines Za8 and ZbB. In the repeater 4 (Figure 6), the winding of the relay SI which is connected to the lines Za, Z is energised and its contact 6i switches in the relay 6A. The contact Ball unlocks the relay 6T, the contact 6M of which unlocks the relay 6G. The contacts gl and B92 open the talking circuit. The relay 6K is thus again connected to the backward signalling line Zb. It responds and the rel-ay ES sends an A. C. impulse to the line V1.2 which energises the relays 5Y and 5X in the repeater iis (Figure 5). The contact 51114 unlocks the relay 5T, the contact 5t4 of which unlocks the relay 5G. The contacts 5g2 and 5g3 close a backward signalling circuit through the lines la and Z214. In the repeaters U2 (Figure 3) and I (Figure 2), the same operations are repeated, the relays 3G and 2G being deenergised. The circuit UD of the recording device is opened. In the nder AS (Figure 1), the relay IM is constantly energised yover the lines Zal, Zbl. The contact Im2 closes a circuit for the thermo-relay lTh which, after a time, closes its contact th and short circuits the winding 2 of the relay IN. The A. C. source BZ is thus switched in and transmits a busy signal to the calling subscriber. The contact lnB opens the calling subscribers feed circuit. When, inv order to make a connection to another exchange, the calling subscriber dials 0, the Vswitch MLWI (Figure 9) closes the contact lclIJ (Figure 1). When the relay IN drops, the winding 3 of the relay IB is energised. A circuit for thejdriving relay AR of a hunting switch RSW is rclosed by the contacts |02, m5 and lb4 so that the wipers rsI-rs3 are stepped in the usual manner until the relay IP responds. The winding 3 of the relay IS of the finder AS which, owing to its delayed release, has not yet dropped, is energised in the'testing circuit of the relayv IP.

scriben The relay: IP startsup another hunting switch RM', thev contacts` of'which are connected to-the line ld I'. 'Ihe` wiper rm Is isthus steppedl forward untiLitreaChes the line Zdwhen a circuit supplied from the A. C. source Q is made through the wiper rs3. The alternating current energises a relay. ITwhich. stops the hunting' switch RM and brings a. current. impulse-transmitter (not illustrated) into; action; for the emission of impulses in accordance witlrthe setting ofthe wiper rml. These impulses are transmitted by the Contact z' through; the wiper 2:82. to the line Zal, 'Ihey are characteristicof the number of' the calling sub- At the end. of vthe impulse transmission, acontact xfisopened and de-energises the relays IS andY IP. Thel contactv |52 then opens the circuit throughthe line lcI and. thus. brings about thegrelease off the connection. The impulse trains which, are sent, out by the contact. z'- are transmitted by the; repeater UI to the line-VLI. rThe relays SJTandA in therepeater 2 (Figure 3) transmit; theimpulses to the circuit' JD of the recorder whichl then prints the calling subscribers, number; The connecting devices which lie beyond the repeater. 2gin which the recorder is ber of'. the exchange (Figure 9)' in which theY switch MLWZisarraIiged", the relays 4U', 4T and 4Rlare-energisediin'succession through the wipersA e dritt an'ddm; The contact 4t4opens the testingcircuit; of. the hunting switch SW2 and the contact?, 415].y starts the driving magnet 4DV of the hunting; switch Silvav which. seizes a free groupvr selector GrW4v in thel exchange whereuponV the=rel-ay4Q is;- energised; The linefV-L2 leading' to; the-mainexchange HA is released and theconnection'isiinallyfmade through the connect.

ing apparatus-ofthe grounfexchangefby the shortiest path, to the-wanted subscribers exchange.

vIn ther case, ofv a semi-automatic connection which is made` by an operator, theV following switching operations are ei'lected.` When the; calling subscriber. removes his receiver and dials. 0,. he is. connected; asin the ,case-oi; afully automatic connection, tothe repeater U4 (Figure 6) of .z the main exchange 1 HA over f thev lines VL I 1 and VLZ. In order to call the operator; the subscriber-` hasv to dial 0. again; The-impulses thus emitted are transmitted over:` the linesfVLI' and VLZ andcause the'group selector GW!l (Figure 7') to be set onto its tenth contact rowout ofwhich ii',.se le.ctsfa1 free line. PL-sothatthe relay 1C is energised. The. ten'impulses also'act upon the relay IEA4 of theswitch MLW 2 Y. (Figurei) in the exchange-` KA, thewiper of which isY stepped; on to a. contact connected tol the relay 4W. The relay4W is energised and -locked.

Whenl the relay 'F.C. (Fig-ure 7) in the main exchange'IAis energised, a circuitl isclosed for a relay 'IAn which causes the hunting switch SWZ of a free operators-position to be set on to. the4 line PL. which was,V seized by the gIOUD- selector GWL The relays.V 'IP and 'IT'are energised and respond. 'Ihe contactlp4- switches in a signal lamp AL and the contacts lp! and 1102. connect 'the` operatorsspeechglineto the line PL.

The contact 'lp .closesthe circuit offthe. relay lV" which. responds. after; aA delay. A backward sig- (Figure '7) a relay 'IWKFigure '7) isv de-energised, b'y the-contact Abfl and, after ai delay; releases..

The contacts lm fand AbfZ close a, backward signalling circuit throughthe lines Zbl, Zb5 for the duration-'oi the delay'in release of therelair 1W.

Asecond backwardsignal is thus transmitted in the same way asthelbackwardsignal is'givenby' the iinal selector in 'a completelyautomatic connection when the` 'called subscriber takes up his receiver. In the.repeaters, the relays 6P6G, 5P, 5G, 3P, 3G,'2P and 2G are energised.l In the finder-'AS (Figure 1), the relay IGfisenergised. The speechcircuitsfarev thus closed in the finder Vand in allthe repeaters. 'I'he'op'e'rator can nowV take the calling subscribers instructions.

vTo make the wanted connection, the operator' opens-thekey AbfA and actuates the selecting key WS (Figure 7). The Contact" WSI. opens the circuitr through the relay IV which drops. after adelaysof about 300millisecond`s, for which periodV a. backward signalling circuit is closed through the lines Zbl, Z215; `la5, Zalv by the contact lvl.. This backward signal corresponds tothe signal given by the final selector in a completelyA automaticzcon'nection when the called subscriber puts back his:v receiven During the transmission of thissignal, thev following operations take place in the repeaters.

In vthe repeater 4 (Fig-ure 6), the relays 6J and 6A are'energisedv andthe relays 6T and 6G' drop. The relay 6G opensY the talkingA circuit and connects the relay 6K to theA backward 'sig` nalling line`4 Z55 so that this relayresponds for'v the*durertiorrof1 the backward signal. The relays 611,768 send anI A. C. impulse overthe line VL2. When, on interruption ofl the baokwardsignalling circuit at the operators position, `the relay 6K e drops, the'relay SZ is energised by the contacts 67c4`, 6-'p5 and is locked. The relaysr 6L, GS then sendasecond backward signalling' impulse over' the li'neVL2'..V y l In the repeater (Figure'), on receipt of the rst' backward signalling,k impulse, .theerelays SY and, 5X lare energised andopen the circuits of the relays 5Tand 5G., The backward. signal is`transmitted over the linesA la4 and Z174. When, on receipt of the second backward. signalling eurrent impulse, the relay EY drops, they relay SZ is energisedfby the yContact 5y4, 5.175 and closes a lockingvjjcircuit. The same switching operations take place in the repeaters Z and I (Figure-3). as in the repeaters 4 and 3; VIn the finder AS, onreceipt of the backward signal, the relay; IM is energisedY andi closes a circuit for'the two-step relayel which; makes its rstistep and closes its Contact HI I. When, at the end ofthe 300 millisecond backward signal; the relay IM drops, the

relay IF, makes its second step andI the contact lf2/2' unlocks the relays IG vand IS so that the talkingfcircuit isopened.. The contact U23-again circuits the winding 2 of the relay IB'which drops and opens the circuit of the relay IF. The finder isnow in the condition ink which it is before a subscriber starts to dial. In the repeaters I- to nalling circuit is then 'closed1 through-the lines-' exactly the 4, the counting relays T, P, G are de-energised but the relays 3Z, BZ and BZ in the repeaters U2 to 4 are energised.

When the operator dials, the relay IA is energised by the impulse contact usi. The contact 'Ial sends impulses to the line la'I and thus to the relay 8A of the group selector GWZ which is therefore set. At the same time, the contact 'Ia2 sends impulses over the lines Zbl, Zb5. In the repeater U4, owing to the energisation of the relay 5Z, the relay SS is connected to the backward signalling line lb5 and transmits A. C. impulses through the line VLZ. In the repeater U4 (Figure 6) there is an impulse responding switch MLW3, the driving magnet (iDm of which is actuatedby the impulses sent out by the operator through the contact B185 and steps the wiper SdM.

In the repeater S, the impulses are received by the relay 5E and are transmitted by the contacts 5cl and 5e! over the lines Z124, Zb3. In the repeater Z (Figure 3) the relay 3R is connected to the line Zb3 by the contact 32| and its contact 3r2 transmits the impulses over the line ld3 to the relay 4A of the switch MLW2. The magnet 4Dm steps the wipers dmI-dm4 in accordance with the impulses sent out by the operator. As the relay 4W is energised, the wiper dm2 is effective. If the operator dials the number of the exchange KA through which the calling subscriber is connected to the operators position, the wiper of the switch MLW3 (Figure 6) comes on to a contact to which is connected the relay 6U while the wiper dmZ of the switch MLW2 (Figure 4) comes on to a contact to which are connected the relays 4T and 4R. On energisation of the relay 6U, the driving magnet BDm is disconnected by the contact 6u! so that further impulses from the operator are unable to inuence the switch. The contact 6u2 closes a circuit through the line ld5 so that the relay IU (Figure 7) is energised. The contact 'Iul opens the testing circuit for the group selector GW! so that the connection made through this group selector is released. In the switch MLW2 (Figure 4), on energisation of the relay 4T, ya circuit is closed for the driving magnet 4DV of the hunting switch SW4 which seizes a free group selector GW4 (Figure 9) of the exchange KA. The relay 4Q (Figure 4) then responds. The testing circuit of the hunting switch SW2 remains closed at first through the contacts 4w3, 4112. The contact 4r! prevents the switch MLW2 being further influenced by impulses from the operator which are transmitted by the contacts 4a5, 4t5, 4105, 4ql, to the not illustrated group selector in the exchange KA. A connection is thus made by the shortest route through the group selector of the exchange KA. All impulses which are used by the operator for making the connection are also transmitted by the contact 31'! (Figure 3) to the circuit JD of the recorder ZD which records the dialled number.

If a nal selector, such as the selector LW illustrated in Figure 8, has been set by the impulses sent out by the operator on to the wanted subscribers contact, a backward signal is given as in a fully automatically made connection. If the subscriber is engaged, the backward signalling circuit through the line Z228 is held permanently closed in the final selector; if he is disengaged, the backward signalling circuit is only momentarily closed.

If the connection made by the operator runs through the group selector GW2 (Figure 7), the

relay 'IM is energised in the backward signalling circuit. The contact 'Im3 transmits the backward signal to the line lbiI, and thence, in the manner already described, to the iinder AS (Figure 1) which, in the event of the Wanted subscriber being engaged, causes the release of the connection. As long as the operator has not restored the key WS to its normal position, a circuit for the relay 'IL is closed by the contact 'Im3 so that the contact 'Ill switches in a lamp BL.

If the relay IM is only momentarily energised by the idle backward signal, a circuit is closed for the relay 'IQ when the relay 'IM drops. The relay 'IQ is then locked and its contact Iq2 closes the talking circuit and disconnects the relay 1M.

In the repeater (Figure 6), on receipt of the rst backward signal after the connection has been made, the relay 5S is energised. The contact 654 short circuits the relay GZ so that the latter drops. The relay 6K is then again connected to the backward signalling line lb5. The further backward signals are transmitted in the manner already described. In the repeaters 3 (Figure 5) and 2 (Figure 3), the relays EZ and -3Z are also short circuited. The transmission of the signals indicating removal and replacement of the called subscribers receiver are thus effected in the same manner as in the case of fully automatic connections.

If the impulses sent out by the operator cause the connection to the wanted subscriber to be made through the hunting switch SW4 and the group selectors of the exchange KA, the backward signals given by the nal selector are received by the relay 4M which transmits them to the line ID3 by means of the contact 4ml. On receipt of the rst backward signal after the nal selector 'has been 'set which indicates whether the wanted subscriber is free or engaged,

the relay 4N is energised by the contact 4m2 and is locked. The contact 4n2 opens the testing circuit for the relay 4P so that the relay 5C in the repeater U3 drops and opens the circuit of the sloW-to-release relay 5U. The relay 5A is energised for the duration of the delay in dropping of the relay 5U and sends a long A. C. impulse to the line VL2. In the repeater 4 (Figure 6), the relay 6C is thus short circuited and the cir- -cuitof the relay 6E is then opened. The contact SC3 opens the seizing circuit of the group selector GWI so that the latter is released. The line VL2 between the exchange KA and the exchange HA is thus released.

y Int'he case of a connection made directly over the selectors of the exchange KA, the idle signal and the signals denoting the removal and the replacement of the called subscribers receiver are transmitted to the nder AS in the .same manner as in the case of fully automatic connections. The speech circuit is closed in all repeaters and in the nder by the signal denoting the removal of the receiver. 'Ihe signal denoting the replacement of the receiver brings into action the device which determines the calling subscribers number and transfers it to the recorder ZD.

The operator does not need to supervise the connection she has made. All she has to do is to take instructions from the calling subscriber and to send out `the selecting impulses for making the wanted connection. When she has done this, she is again free to make a new connection. For evaluating charges the same apparatus (a fslip printing device or a time-zone metering dea2ac, 99,8.;

vice) lisgusedvas in the case-.of connectionsrwhich:

are made fully automatically.

Instead: of the inal selector showninFigure-,

selectors which allow the operator. toconnect-g herself to a busy subscribers line andto sever.' the existing connection can beused. Such-rse.-y lectors are knownin themselves; i

In,- the system illustratedin Figures. 10`l.72.;;a;v subscriber belonging to a terminal exchange' EA. orto a subsidiary `group exchange. KAto: azmairrY groupexchange I-IAA can bydialing; O `be .connected inknown manner to the selector SGrWY of. the

central exchange ZA from which. radiate-lines:

leading to other-main group-exchanges I-IA.. .The second digit dialled by .the-subscriber.' causes the group-selector. SWG to be set at. a.group.selectorf GW l which fthrough-afurther groupselectorlGWZ. may seize a line4 VAV leadingto the wanted-main'v group exchange to be seized in. a. circuitmade through the group. selectors SWG, GW'I and" GWZ. The subscriber can. then-himselfn establishvv the connection to the' wanted subscriber; Be-

tweenthe calling. subscriber and. the centralex'.-

change ZA', there is a recording deyicexZD/which--V is here assumed to be a. printing device` whichunder theiniiuence ofthe impulses sent. out by the calling subscriber records. the wanted:v subi-1 scribers number, his exchange, the durationof the call and the calling subscribers number;V J

IfA the second digit dialled by the callingsube- Si scriber is 0, the selector` SGW at the. central-.exchange ZA. is set on to a line which' leads to the operators position APZ. The relayl ZC (Figure 1l) is energized over the lihey lc 'and'v closes cir;-

cuitsior the relays 2Q and 2An'. Thercorrtact: 2an2 closes a circuit for-theV drivingmagnet' ZDS.A of ta hun-ting switch SW which connects the con-ff necting` devicesV of' the operator-s position API to; the line PL which is seized-bythe. group-selector SGW. When the wipers ofift-h'e;1 hunting-- switch- SW reach this line, therela-ys ZEUand 2S1are v:ener- The contacts 2511-" gised through the wiperf dsc. and 2s2 connect theoperators speechwires.; the Contact 2's3 switches ina signal lamp AL;-=the -contact 2.94'. closes a circuit for a sloW-to-respond relay 2V and the Contact 285 afcircuit for a slowto-respond relay 2W. For the duration-of the delay in response of the relay 2V, a backward signalling circuit is closed 4through the line lb by the contacts 2v2 and 252. The impulse thus sent causes an idle signal to be transmitted-over the calling subscribers feed circuit.

When the operator actuates the key Abi; the circuit of the relay 2W is opened by thev contacty Abf3. The relay 2W drops after a delay for theA l' duration of which a circuit is closed through the line Zh by the contacts 2w| and AbyZ. The relatively long impulse thus sent. back causes the idle signal torbe switched off inthe calling subscribers feed circuit and speech lines to be conneoted up. It also causes the speech-circuits to be closed in the repeaters through which the connection has been made.

The operator at the position APL can now speak-to the calling subscriber andtake his. in- I structions. To connect the subscriber to another subscriber of the same network, theoperator actuatesV the dia-l WS. The contact' WSS then opens the circuit through the relay 2V. This relay drops after a delay during the duration of which a circuit is again closed through the line lb by the contacts 211| and WS2; The impulse thus sent back causes the speech. circuits to be opened. in the repeaters and in the calling subscribers feed circuit. The operator now-actuates her-'dial'. jtlie. contact ns1; of; which energisesthegrelay 2J.. The contact12i-I sendsfimpulsesto the: line la.: which act; onthe relay 2A oithegroup@` ,selector-FGW.' TheY contact 21'2. sends. impulsesv f. has-,been completed; the, nalselector--momen-- tarily Y closes a; backward signalling.; circuit: through one speech wire in which 'the relay.- (Figure 1l) isenergised; The contactf2'm4-v then short circuits the relay 2Q While the contact12fm2:

- lockstheyrelay- 2M which-is unlocked: again; wheny In-y the.I meantime,v the-` contact 2m3.- closest abackWardsignalling circuit through theline lb,- Which causes an idle signal tube-transmitted. over thecalling subscribers feed. circuit. The contact 2121.4i opens the circuit ofthe1relay-2S1and: thus disconnects.. the operators-y position 'APZL- When the called subscriber; replies, a'. further backward `signal' impulse is sen-tv byf thefinal .selector through. the; speech. wire-Which, owing to.v

the dropping vof vthe relayfZQf (Figure-l 1l) isnowv connected. by the: contact 2111.-- to, the line lb. This; impulse closesfthe speech circuits in the repeaters; and in the: callin-gsubscribersi feed circuit. The

i' beginningl of the conversationis atthc same-time recorded on` the' slip; printing mechanism; ZD,` (Figure l0) When theca-lledsubscriber replaces his* receiver, a backward signalling circuit through.. the4 liner lb: is permanentlyT closed` by htheenal-selector which-opens'the speech circuits inthe repeaters. Furthermore; an auxiliary device is causedto send` out impulses corresponding; to. the called subscribers number tor the,y slip printingfdevice ZD which records that number;

.. The connectionr isthen-4 released. in. known.'- marl-.-

ner. y f

Ifthe. callingsubscriber wisheslto"v be connected-to a subscriber who canonly-be reached-- through a long distance operator'atthe positionA -PBZ. (Figure 16)-, the operator. at the-positionAPZ,

after actuating:theselecting-key WSdials 0 and thus setsthe group selector FGW` on toY a; line which-leads to aireeselector FLW. The-tenimpulses thus;sent.out are transmitted in the man- :.:nerdescribed` aboveover theV line lb tothev con--` nection made betweenfthe calling subscriber and: theoperators. position APL and -aotupon thevslip'- printing device ZD. The-operator API by diallingoneor two more'. digits makes a connection- :'through-.theg-selector FLW (Figure 12) to a longel distanceI operators positionBPl from Whichiruntrunk lines The. impulses are also trans-V mitted over the line lb to the slip-printing device. ZD.

.Whenv the selector. FLW isset, therelays.3B. and 3C. are energised.. The contact.. 3012lv closes. a circuit through a relay 3E so thatv the contact Sel connects therelay 3A,t'o the line Zai. At the. long-distance position BPZ there is a number indicating device NA which is actuated by thev drivingmagnets Dl-Dit. The circuits of these driving magnets are successively closed'bya controlswitch the-'driving magnet' 351 of which ismomentarily energised after: each impulse-train.`

When the operator at. Allfsends furtherini--Y pulse trains which characterisev the wanted connection, for example, the wanted subscribers exchange, the relays 3V and 3R are energised during each train which is transmitted over the lines Za, Zal to the relay 3A. When the control switch is in its position I, the contact 30,2 transmits the impulses to the driving magnet Dl. At the end of the train, the relays 3V and 3R, after a delay release one after the other. The contacts 3rl, 31:2, temporarily close a circuit through the control switch magnet 3S so that the latter is stepped into its position 2. The impulse trains are thus transmitted to the driving magnets Dl--D4 of the indicating device NA. Theyare also transmitted from APZ in the manner described to the line Zb and act upon the slip printing device ZD.

When the Control switch reaches its position 5, a relay 3Z (Figure 12) is energised so that the contact 322 opens the circuit of the relay 3E. A backward signalling circuit is closed through the line Zbl for the duration of the delay in release of the relay 3E by the contacts 32| and 3e2, so that the relay 2M of the selector FGW drops.

The relay 2Q is thus de-energised in the manner already described and a backward signalling circuit is temporarily closed through the line lb. When the relay 3E has dropped, the contact 3s3 (Figure 12) switches in the lamp SAL. When the operator at BPZ actuates the switch AF, a slow-to-respond relay 3L is energised by the contact AFS. A backward signalling circuit is closed through the line Zbl for the duration of the delay in response of the relay 3L by the contacts 3Zl and AF2. When the relay 2Q (Figure 11) drops, the line Zbl is connected to the line lb. This backward signalling circuit causes the speech circuits to be closed in the repeaters. The operator at BPZ can now speak to the calling subscriber and obtain the wanted subscribers number. The operator can then connect herself in known manner to the long distance line FL by actuation of the switch VS and call the operator at the other end of this line in order to make the desired connection. When the connection to the wanted subscriber has been made, the operator at BPZ connects the calling subscriber to the long distance line FL and notes the beginning of the conversation on a call slip. The operator also enters on this call slip the number which was set on the indicating device NA.

At the end of the connection, the operator at BPZ actuates the key TTT. The relay 3P in the selector FLW drops and the contacts 3q4 and 3102 close a backward signalling circuit through the line Zbl which is connected to the line lb (Figure 11). The permanent backward signal causes the speech circuits to be opened in the repeaters. Furthermore, in the calling subscribers exchange the auxiliary device is started which sends out impulses to the slip printing device ZD in accordance with the number of the calling subscriber.

The impulse trains by means of which the operator at APZ makes the connection to BPZ are transmitted to the slip printing device ZD, the calling subscriber and the operators position APZ. The two digit or three-digit number thus recorded can .be used to indicate that the connection runs to a certain district, region or country. As the operator at BPZ makes an appropriate note upon the call slip, and the time of the connection is recorded both in the slip printing device ZD and also by the operator at BPZ,

it'i's possible subsequently to identify the two call slips.

This identification is facilitated by the supplementary distinguishing marks recorded or shown on the slip printing device and to the number indicating device NA.

The operator at APZ 'can sometimes connect herself directly to BPZ by inserting a plug into an appropriate socket. In this case, only the number indicating device NA need be provided. This is set by one or more supplementary impulse trains which are transmitted at the same time to the slip printing device ZD. The numbers appearing on the device NA may give information regarding the wanted connection, for example the number of the wanted exchange. 'Ihey may, however, be used merely for the serial numbering of the various connections and thus for the identification of the call slip written by the operator at the long-distance position BPZ with the information recorded by the slip printing device'ZD. In any case, the operator at BPZ can immediately make the wanted long-distance connection without it being necessary for a separate connection to be made to the calling subscriber, :because the number of the calling subscriber is clearly recorded by the device ZD.

We claim:

1. A selector operated telephone system 'comprising a plurality of exchanges including a central exchange, a calling subscriber, a called subscriber, a connecting path between said calling subscriber and said central exchange, means for transmitting dialling impulses sent by said calling subscriber over said connecting path, discriminating means associated with said connecting path and controlled by said dialling impulses, an operator at said central exchange, means -controlled by said operator for transmitting dialling impulses to the selectors of said central exchange, and means for transmitting said lastmentioned dialling impulses over said connecting path to said discriminating means.

2. A selector operated telephone system comprising a plurality of exchanges including a central exchange, a calling subscriber connected to a calling exchange, a called subscriber connected to a called exchange, a connecting path between said calling exchange and said central exchange,

means for transmitting dialling impulses sent by.

said calling subscriber over said connecting path, discriminating switches associated with said connecting path and controlled by said dialling impulses oi said calling subscriber, a selector in said central exchange connected to said connecting path, an operator in said central exchange adapted to be called by the setting of said selector on to a predetermined level, group selectors in said central exchange adapted to be seized by said selector on its being set on to another level, means controlled by said operator for transmitting =dial ling impulses to said group selectors of said central exchange, means for transmitting said dialling impulses of said operator over said connecting path backwardly to said discriminating switches, a discriminating switch in said central aangegesituated between said calling exchangefand; sai-d; central exchange, a connecting path between said calling exchange and; said central exchange, acalled subscriber connected to said intermediate` exchange, a discriminating switch in said' intermediate exchange for preparing selectors` of said exchange, means for transmitting dialling impulses sentV by said calling subscriber over said' connecting path, means controlled by said 'dialling impulses for setting said discriminating vswitch of said intermediate exchange, an operator associated with said kcentral exchange, group` selectors associated with said central exchange, da-lling impulse emitting means controlled by said operator, means controlled by said dialling impulses of said operator for setting saidl group selectorsV and means for transmitting saiddiallingv impulses oi said operator over said connecting path to said discriminating switch'of said intermediate exchange.

4'. lIn anv automatic telephone system in which a subscriber can make a call at will either directly or through an exchange operator, the provision of' means whereby impulses sent out by the operator toextend the connection towards the wanted exchange are also ltransmittedbackwardly over thev connection already made between the calling subscriber and the operator.

5;. An automatic telephone system comprising a plurality ofexchanges including a -calling subscribers exchange and an attended exchange through which all calls from said subscriber's exchange to another exchange are made, and means at said attended exchange under the control of the operator of saidexchange for the transmission of current impulses forwardly towards the called subscribers exchange and simultaneously backwardly towards the calling subscribers exchange.

6. An automatic telephone system as claimed in claim 5 comprising between said calling subscribers exchange and said attended exchange means for recording data for use in evaluating the charge to be made for a call, said means being acted upon by said backwardly transmitted impulses.

7. An automatic telephone system as claimed in claim 5 comprising between said calling subscribers exchange and said attended exchange means for routing a connection, said means being acted upon by said backwardly transmitted impulses. Y

8. An automatic telephone system comprising a plurality of automatic exchanges including a calling subscribers exchange, a called subscribers exchange, an exchange provided with an operators position and an exchange between said rst and third mentioned exchanges, means under the control of a subscriber of said first mentioned exchange for connecting said exchange through said fourth mentioned exchange to said third mentioned exchange and for calling the operator over the connection thus made, impulse transmission .means under the control of said operator for connecting said third to said second mentioned exchange through said fourth mentioned exchange, said last mentioned means being eiiective also to transmit impulses at the'same 'time over the -connection made between said first and said third mentioned exchange and means actucalling:A subscribersi exchange, an attended ext' change,.fa called subscribers exchange, an: ex- -change intermediate said calling and'` attended exchanges and said attended and called. exchanges, means under the control of a subscriber of saidl calling exchange'. for making a connection from saidicalling to sai-d attended exchange through said attended' exchange and for'calling the operator at said attended exchange over said connection, means under the control` of said' operator for 'extending said connection to said called exchange through said intermediate exchange, sai'd last-mentioned means being effective to transmit impulses simultaneously forwardly over the extended connection and backwardly over the connection made from said calling exchange, a nal selector at saidcalled exchange adapted to b-e actuated by' saidimpulses, means controlled by sai-d final selector for sending back a signal indieatingl that said' selector has found a free outlet and means at said intermediate exchange adapted, on receipt of said signal, to release the connection between said intermediate and attended exchanges;

10. An automatic telephone system as claimed in claimV 5 comprising meansr at" the wanted ex= change for sending backv signals indicating that a wanted line is idle andrthat the wanted subscriber has removed his receiver, and means at the attended exchange or sending back similar signals indicatingY that the operator is free and that she has removed hery receiver.

11,.V An automatic telephone systemas claimed in claim-5fcomprising means" at the wanted exchange for sending backA signals indicating that awanted line is idle and that the wanted subscriber has removed his receiver, means at the attended exchange for sending back similar sig.- nals indicating that the operator is free and that she has removed her receiver, and means actu- .ated by said last mentioned signal for closing a talking circuit between the calling subscriber and the operator.

'12. An automatic telephone system as claimed in claim 5 comprising means at the wanted exchange for sending back signals indicating that ra wanted line is idle and that the Wanted subscriber has removed his receiver, means at the at- Y tended exchange for sending back similar signals ated by said impulses for breaking the connection between said third and fourth mentioned exchanges.

9. An automatic telephone system comprising a indicating that the operator is free and that she has removed her receiver, means actuated by said last mentioned signal for closing. a talking circuit between the calling subscriber and the operator and means under the control of the operator for opening the talking circuit without breaking the connection between the attended and calling exchanges.

13. An automatic telephone system comprising a calling subscribers exchange, an attended exchange, a called subscribers exchange, means under the control of a subscriber of said calling exchange for transmitting impulses, means controlled by said impulse-transmitting means for Y makingv a connection to said attended exchange and for calling the operator at said attended exchange over said connection, at least one repeater through which said connection is made, means for sending to said calling subscriber signals indicating that the operator is free and that the operator has removed herreceiver, impulse transmitting means under the control of said operator for extending said connection towards said called f exchange and meansv under the control of the 

